Javascript && operator logic

Question

I'm developing a controller in angular. For some reason there is an If statement that is giving me a issue, yes an if statement.

The code is the following:

$scope.new = function(logoFile) {
if($scope.comprobarCampoDesc() && $scope.comprobarCampoFecha() && $scope.comprobarCampoName() ) 
{ 
//program logic
}

Also there is the other pieces of code:

$scope.comprobarCampoName = function(e) {
//program logic
return bol;
};


$scope.comprobarCampoDesc = function(e) {
//program logic
return bol;
};


$scope.comprobarCampoFecha = function(e) {
//program logic
return bol;
};

Ok, For any reason that I'm not able to identify, the if statement only checks 2 of 3 methods, depending of the order. In this concrete case it is ignoring "$scope.comprobarCampoName" but if I change the order other method is witch doesn't work.

Thanks for the help. Greetings.

Does it always check 2 of 3 methods or only if 2 of 3 methods are returning true ? — Vollmilchbb
– Vollmilchbb, Commented Nov 17, 2015 at 12:16
well you must know the && operator only evaluates the next operand( functions in you case ) only if the operand before evaluates to true or equivalent. — Minato
– Minato, Commented Nov 17, 2015 at 12:16
It's strange because all of the operands are false and allways execute 2 of them. Anyway thanks for the help. Finally I join the three methos in one in order to do only one call in the if statement. — ssg
– ssg, Commented Nov 18, 2015 at 10:18

Deblaton Jean-Philippe · Accepted Answer · 2015-11-17 12:16:45Z

2

In your case, if one of the conditions is equal to false, the if statement stops and does not iterate further.

If you really need to execute each of those, I recommend you to do the following :

var first = $scope.comprobarCampoDesc();
var second = $scope.comprobarCampoName();
var third = $scope.comprobarCampoFecha();

if (first && second && third){
   // execute
}

answered Nov 17, 2015 at 12:16

Deblaton Jean-Philippe

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1 Comment

Paul-Jan Over a year ago

The official term for this behavior, which is very common in programming languages, is Short-Circuit Evalution. See developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

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